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Dynacomp --> Janglebox Mod: Is this the right capacitor?


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I've read that the Janglebox is basically a Dynacomp that doesn't filter the highs back out at the end. I've also read that you can convert a Dynacomp to work like a Janglebox by clipping or removing the capacitor that's "parallel to the 150k resistor on the output of the chip"... Is anybody familiar with this mod? Can anybody tell me if I've circled the right cap in this picture?

Thanks.

 

ry%3D480

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Parallel to the resistor could mean electrically running in parallel, not that they're sitting parallel next to each other on the board. I am not saying that's not the right part - I have no idea either way. This is the first I've heard of the Janglebox / Dynacomp thing. Where did you hear that?

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It's the 1n cap that's attached to pin 6 of the IC. I can't tell from that (your highlighting has covered the traces! :D) but if you can follow it from pin 6 you should find it ok. It'll either be the one you have noted, or the similar cap perpendicular to it at the bottom.

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Thanks for the quick reply Phil. That cap is parallel to the resistor both in position and in the circuit. On the lower end (probably covered it with the oval) there's a trace connecting them and on the upper end there's a trace on the back side of the board connecting them.

 

I read about the mod here (6th reply):

http://www.madbeanpedals.com/forum/index.php?topic=1463.0

 

and here:

http://music-electronics-forum.com/t16262/

 

and this:

The Janglebox has a "Bright/Normal/Dark" switch - in the normal setting it is like a Dynacomp; basically, the Dynacomp boosts the treble a bit before the compression stage of the circuit, and cuts it again after that stage (probably to get less noise) - what that switch on the Janglebox does in the "Bright" setting is getting rid of that treble-cut cap after the compression stage (so the treble remains boosted), and in the "dark" setting cut out the treble boost before the compression stage.

From here:

http://www.shortscale.org/forum/viewtopic.php?t=30921&sid=a340a6af5f743e49fe4e9fab960ab463

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I am unfamilar with the MXR board you have there, and i cannot read the resistor codes in your photo, but that is roughly in the space that i would expect the cap you are looking to remove, to be located.

 

It should be a 150k resistor and a 0.001uF capacitor, connected to each other on both ends. On one side they should go to pin 6 of the CA3080 IC. On the other side, they should go to a 27k resistor, which then is connected to ground.

 

The Janglebox is a little bit more than just the cap removal, but taking out that cap will basically provide the brightest setting of the janglebox. I would suggest putting it on a switch so that you can retain stock functionality. I personally find both modes useful.

 

EDIT: i type very slowly? :lol:

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Thanks for the quick reply Phil. That cap is parallel to the resistor both in position and in the circuit. On the lower end (probably covered it with the oval) there's a trace connecting them and on the upper end there's a trace on the back side of the board connecting them.


I read about the mod here (6th reply):

http://www.madbeanpedals.com/forum/index.php?topic=1463.0


and here:

http://music-electronics-forum.com/t16262/


and this:

The Janglebox has a "Bright/Normal/Dark" switch - in the normal setting it is like a Dynacomp; basically, the Dynacomp boosts the treble a bit before the compression stage of the circuit, and cuts it again after that stage (probably to get less noise) - what that switch on the Janglebox does in the "Bright" setting is getting rid of that treble-cut cap after the compression stage (so the treble remains boosted), and in the "dark" setting cut out the treble boost before the compression stage.

From here:

http://www.shortscale.org/forum/viewtopic.php?t=30921&sid=a340a6af5f743e49fe4e9fab960ab463

 

 

Thanks for the links Chris. :cool:

 

Pre-emphasis (boosting treble) / de-emphasis (cutting treble) is a commonly used noise reduction technique - tape deck noise reduction circuits like dBx use it. I can't imagine it was put into that design for any other reason than lowering noise.

 

Hey chris_d, what other differences are there to the Janglebox? I didn't realize it was based on the Dynacomp - not that that's all that unusual for compressors...

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Thanks for the quick reply Phil. That cap is parallel to the resistor both in position and in the circuit. On the lower end (probably covered it with the oval) there's a trace connecting them and on the upper end there's a trace on the back side of the board connecting them.


I read about the mod here (6th reply):

http://www.madbeanpedals.com/forum/index.php?topic=1463.0


and here:

http://music-electronics-forum.com/t16262/


and this:

The Janglebox has a "Bright/Normal/Dark" switch - in the normal setting it is like a Dynacomp; basically, the Dynacomp boosts the treble a bit before the compression stage of the circuit, and cuts it again after that stage (probably to get less noise) - what that switch on the Janglebox does in the "Bright" setting is getting rid of that treble-cut cap after the compression stage (so the treble remains boosted), and in the "dark" setting cut out the treble boost before the compression stage.

From here:

http://www.shortscale.org/forum/viewtopic.php?t=30921&sid=a340a6af5f743e49fe4e9fab960ab463

 

 

Thanks for the links Chris. :cool:

 

Pre-emphasis (boosting treble) / de-emphasis (cutting treble) is a commonly used noise reduction technique - tape deck noise reduction circuits like dBx use it. I can't imagine it was put into that design for any other reason than lowering noise.

 

Hey chris_d, what other differences are there to the Janglebox? I didn't realize it was based on the Dynacomp - not that that's all that unusual for compressors...

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I don't have the jB schematic in front of me at the moment, but aside from the obvious difference of the third, "dark" mode(which IIRC, and logically, is simply a larger value than stock cap), there were several changes to various parts of the circuit that are less likely to make any obvious sonic difference. Stuff in the power supply and whatnot.

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Glad I wasn't brave enough to clip it first. It turns out to be this cap and resistor down lower. Good news is this one's in an easier spot to run wires to a switch since it's not so directly under the sensitivity pot.

ry%3D480

 

Which model do you have? I think mine's a reissue. It doesn't look like this ????

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it would be funny if the sound difference is just that one resistor, given all the stuff they say on the Janglebox website about how they set out to build a special compressor circuit and hired an engineer to design it and all of that.

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Having no technical knowledge, I will say this, having played both a Janglebox and a Dynacomp, if the difference between them is just that one resistor, then MXR royally fucked up putting that resistor in there, because the Janglebox sounds miles better.

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big_cat:

this page has links that show what 4 dynacomp versions look like.

http://www.monteallums.com/pedal_mods.html#mxrdyna

you may have to scroll down a bit, the links are called "Vintage", "Revision D", "Revision E", "Revision F" and my dynacomp is a revD which it also says on the board. You should still be able to find a cap parallel to a 150k resistor coming from the chip output. On mine the pcb sais c4 under the cap. The chip was tucked under one of the pots on mine.

My advise though is don't do it until I have a chance to test it out in case its somehow wrong.

I put it on a switch but I wont have a chance to plug in and play untill probably friday.

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thanks chris! dont have it in front of me at work but it looks like mine is a revision e or f. i'll wait until you report back.

 

i don't really like the dynacomp as it is, i'm basically using it as a boost for my low output lap steel.

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Sorry for taking so long but I finally had a chance to play with this thing...

 

It's AWESOME!

 

It still does the basic dynacomp thing (which I like) but with this new bright chimey goodness. When I switch the cap in and out it's like adding and removing a wet blanket. However, compared to the bypassed signal it's pretty bright and I guess you could call it thin. Sounds really good but doesn't have the same big bottom as the bypass tone. I'm playing a Les Paul through a Fender so the brighter thinner sound works perfectly. Someday when I'm bored (right...) I might find a much smaller cap to put in its place to just take the tip top of the highs back off but for now it's fine.

 

I think I can really dig this compressor now!

 

ry%3D480

 

ry%3D480

 

ry%3D480

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  • 7 years later...
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Hi everybody!
Reviving this olddddd thread to get a little more info on this mod if possible.

I have the same MXR dyna comp version as pictured above- and I want to do the exact same mod.
Im relatively new to electronics, however Ive built a number of pedal kits successfully.
Can anyone tell me the details of this mod? Do I simply remove the cap and resistor that are circled above? Im not super bothered to be able to switch it in and out, but if its easy enough I would go that route.
Any help would be much appreciated, I want a janglebox on the cheap!
Thanks in advance

C

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You can put in a switch so you can take the cap (and resistor too? I don't recall if I pulled both out since it's been so long since I modded my DynaComp) out of the circuit whenever you want while keeping the stock configuration readily available, or you can just pull them off the board if you don't want the ability to quickly change between stock and modified configurations. I didn't bother with a switch since I have several other compressor pedals. I don't recall if you need to jumper the contacts once you remove the components or not. I'll try to do a little research (and maybe open my DynaComp and take some pics) later today and get back to you.

In the meantime, I'd recommend checking out all of the links listed in the thread and doing some more research. I did my mods based on that information, and the information contained in the posts in this thread. 

BTW, welcome to Harmony Central! :welcome:

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38 minutes ago, Phil O'Keefe said:

You can put in a switch so you can take the cap (and resistor too? I don't recall if I pulled both out since it's been so long since I modded my DynaComp) out of the circuit whenever you want while keeping the stock configuration readily available, or you can just pull them off the board if you don't want the ability to quickly change between stock and modified configurations. I didn't bother with a switch since I have several other compressor pedals. I don't recall if you need to jumper the contacts once you remove the components or not. I'll try to do a little research (and maybe open my DynaComp and take some pics) later today and get back to you.

In the meantime, I'd recommend checking out all of the links listed in the thread and doing some more research. I did my mods based on that information, and the information contained in the posts in this thread. 

BTW, welcome to Harmony Central! :welcome:

Thanks Phil! Much appreciated.

Ive been looking all over the place for info. Think im keen to put the capacitor on a switch, but pics would be most helpful and much appreciated.
According to this page: https://www.thegearpage.net/board/index.php?threads/can-i-use-a-2-way-spdt-toggle-to-bypass-a-resistor-or-cap.759830/
I just connect one side of the capacitor to the middle pin of an On/On SPDT switch and the other leg to an outer pin. Hoping thats all I need to do to switch it out and in of the circuit. If anyone can advise me on that id be good to go!

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Okay, the mod just lifts or removes the .001uf capacitor that is next to, and wired in parallel to the 150k resistor on the output leg of the CA3080 - you don’t do anything to the resistor itself. Again, the components you’re looking for are on the output end of the 3080 op amp. There is no need for a jumper to replace the removed capacitor. 
 

You can “lift” just one end of the cap and connect the lifted end to one contact on a SPST switch, and connect the other contact on the SPST switch to the empty pad on the circuit board (that was previously connected to the now-lifted leg of the capacitor) which would allow you to switch the capacitor in and out of the circuit, giving you both the brighter modded tone and the stock tone at a flip of the switch. 
 

I still need to open my DynaComp and take some pictures. I don’t recall which capacitor number it was, but it is marked on the circuit board. However, there have been multiple revisions of the DynaComp PCB so mine may not be the same as yours, and yours may not be the same as the one pictured in this thread. 

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Okay, looks like I don’t need to take any pictures after all.

 

According to the schematic on this page...

https://www.electrosmash.com/mxr-dyna-comp-analysis

...the correct capacitor is marked C5, and it is right next to the 150k resistor marked R8. 
 

Don’t let the fact that the cap in his schematic is marked 1nf throw you off. 1nf = .001uf. 
 

If you have any more questions, don’t hesitate to ask. 
 

Good luck with your mod and please let us know how it turns out, and what you think of it once you try it. 
 

 

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5 hours ago, Phil O'Keefe said:

Okay, the mod just lifts or removes the .001uf capacitor that is next to, and wired in parallel to the 150k resistor on the output leg of the CA3080 - you don’t do anything to the resistor itself. Again, the components you’re looking for are on the output end of the 3080 op amp. There is no need for a jumper to replace the removed capacitor. 
 

You can “lift” just one end of the cap and connect the lifted end to one contact on a SPST switch, and connect the other contact on the SPST switch to the empty pad on the circuit board (that was previously connected to the now-lifted leg of the capacitor) which would allow you to switch the capacitor in and out of the circuit, giving you both the brighter modded tone and the stock tone at a flip of the switch. 
 

I still need to open my DynaComp and take some pictures. I don’t recall which capacitor number it was, but it is marked on the circuit board. However, there have been multiple revisions of the DynaComp PCB so mine may not be the same as yours, and yours may not be the same as the one pictured in this thread. 


Wow thanks heaps for all the info.
It was a huge help!

Just did the mod (without the switch for now) and WOW it sounds so much better. The highs are sparkly and jangly. I switched the LED to a pink one for fun as well. Sound wise, the difference is night and day to me, as I tried and tried to like the stock dyna comp but it sounded so lifeless and dull.

I play a Rickenbacker 610 with High gains and very little bass in the signal. (I love a tinny guitar). And this complements it well. Instant Byrds sound.
I think ill add the switch later on when it arrives, as Im waiting on an order.

For future reference, my Cap was labelled C4 not C5. I checked and it was indeed next to R8. It was in the same space as the capacitor in the picture above (the second one down the page).

C

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